TALLAHASSEE — No one knows if Florida is going to be the next frontier for the new generation of oil and gas drilling known as fracking, but state legislators say — just in case — it's time to write rules to require disclosure of the controversial technology.

The Florida House is expected to pass a bill today that will require companies to disclose what chemicals they use when they explore for oil and gas using the much-debated extraction process.

Fracking uses hydraulic fracturing technology to inject water, sand and chemicals underground to create fractures in rock formations. Oil and gas is released through the fissures and is captured by wells, built at the sites.

Environmentalists warn that the chemical makeup of the fluid that is pumped into the ground could contaminate groundwater and release harmful pollutants, such as methane, into the air.

"The Fracturing Chemical Usage Disclosure Act," sponsored by Rep. Ray Rodriques, R-Estero, would require the state Division of Resource Management to set up an online chemical registry for owners and operators of wells, service companies and suppliers that use hydraulic fracturing.

The bill also requires the information to be posted on the website FracFocus.org, an online clearinghouse run by the Groundwater Protection Council and the Interstate Oil and Gas Compact Commission.

Rodriques said the bill, HB 743, is neither profracking nor antifracking. "It's a transparency bill," he said. A similar measure is moving in the Senate, sponsored by Sen. Jeff Clemens, D-Lake Worth.

Hydrologists have identified only two potential areas in Florida — Southwest Florida's Lower Sunniland field and the Jay field in the Panhandle — where the state's geology could support fracking, Rodriques said. But if Florida is the next industry hot spot, "no one has applied for a permit" and the Department of Environmental Protection "does not have any active inquiries," he said.

Rodriques said he believes that speculation continues among investors who believe Florida's ancient oil fields may have fracking potential, particularly in Southwest Florida, where a handful of oil wells have operated for decades largely unknown to the public.

In Houston on Wednesday, for example, the second annual conference on "Emerging Shale Plays USA" will feature a presentation on whether or not Florida has the right mix of rock properties to support hydraulic fracturing at the Lower Sunniland site in Hendry, Collier and Lee counties.

Environmentalists initially opposed the measure, arguing it was a ploy to open the state to a process they claim could be disruptive to Florida's fragile aquifers and high water table. But amendments adopted by the House have appeased them, said Mary Jane Yon, lobbyist for Audubon of Florida.

The change requires that companies disclose not only chemicals used in the fracturing process, but also disclose the chemical concentration by mass and the chemicals used for each well. Chemicals make up about 0.5 percent of the fracking compounds, with 95 percent of it water and 4.5 percent sand, Rodriques said.